A damning report on the Australian fashion industry shows 93 per cent of brands do not know where their cotton is sourced from, making it likely child labour and exploitation have been involved. The bulk of the world's cotton is sourced from countries that force children to pick cotton harvests.

According to the report, in Uzbekistan, the world's fourth-largest cotton producer, children as young as 10 are taken out of school and coerced by the Karimov government to put in 70-hour weeks working in cotton fields.

"It doesn't take a rocket scientist to work out that there is a high chance that we're all wearing clothing that has been made by slave labour," the founder of ethical brand Etiko, Nick Savaidis, said.

The Australian Fashion Report, to be released on Monday, investigated 40 companies that own 128 clothing brands sold in Australia, ranking them on the transparency and monitoring of their supply chains and ethical codes.

The report, supported by the International Labour Rights Forum and Baptist World Aid, looked at cotton sourcing, fabric dyeing and weaving and manufacturing.

For years children have been widely used to support the textile supply chain, says Carolyn Kitto, spokeswoman for labour rights group Stop the Traffik.

Of the top 10 cotton producers in the world, including the US, China, Pakistan, Brazil and Uzbekistan, Australia is the only country not to use child labour, the report said.

Brands Supre, Abercrombie and Fitch, Rivers, Lacoste and The Specialty Group, which owns Millers and Katies, were labelled as the worst in the report, from failing to boycott Uzbekistan cotton to having murky standards at the final manufacturing stage.

Rivers and The Specialty Group were among hundreds of Western retailers condemned for their lack of safety measures in April after the collapse of the Rana Plaza factory in Bangladesh, in which at least 1129 garment workers were killed.

Co-author of the report Gershon Nimbalker said the deeper researchers looked into the companies' supply chains - down to the harvesting of cotton by children in Uzbekistan - the more they were concerned there was almost no information available.

"About 40 per cent of companies know who the manufacturers were in the [final] stage but that dramatically drops; when you get to the cotton picking stage that [knowledge] is 7 per cent," he said.

The retail promise of "on-trend fashion at affordable prices" has put enormous pressure on factory owners in India, Pakistan and Bangladesh, Mr Savaidis said.

In order to keep their prices low, subcontractors supplying the cotton and fabric end up using child labour, he said.

Australian Retailers Association chief executive Russell Zimmerman said there was "no simple answer" for companies to better understand their supply chains.

"Companies risk losing customers if they are not aware of how their goods are coming through the supply chain," he said.

Of the companies surveyed, only 20 had boycotted the use of Uzbekistan cotton. About 35 per cent of the cotton used in Bangladesh comes from Uzbekistan, the report showed. The value of imports of Bangladeshi clothes into Australia has grown from $16 million in 2007 to $287 million last year.

Companies including Rivers, Woolworths, Coles, Quiksilver and Lululemon do not boycott the use of Uzbekistan cotton.

Supre and The Specialty Group did not respond to Fairfax Media's questions in time for publication.

A spokesman for Rivers said: "Rivers is not aware of the Australian Fashion Report, the basis or authority for making its allegation, nor indeed its motive for doing so.

"Rivers has published ethical standards for all product sourcing worldwide. It follows these standards."

swhyte@fairfaxmedia.com.au

What companies know

7% where their cotton is sourced from

24% where their garments are weaved, knitted and dyed

39% where their garments are manufactured

Source: Australian Fashion Report